Electronic ignition circuit

ABSTRACT

An electronic ignition circuit may include a logic circuit and an ignition circuit electrically coupled to the logic circuit. The logic circuit may include a microcontroller and a switching circuit configured to switch from a first detonator or igniter to a second detonator or igniter in response to a signal from the microcontroller. The ignition circuit may include a capacitor discharging circuit configured to discharge a firing capacitor through a fuse head. The capacitor discharging circuit may include an ignition switch configured to remain actively closed after the firing capacitor is discharged through the fuse head.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a continuation of U.S.application Ser. No. 17/533,734 filed Nov. 23, 2021, which is acontinuation of U.S. application Ser. No. 16/776,977, filed Jan. 30,2020 (issued as U.S. Pat. No. 11,215,433 on Jan. 4, 2022), which is acontinuation of U.S. application Ser. No. 15/880,153, filed Jan. 25,2018 (issued as U.S. Pat. No. 10,605,578 on Mar. 31, 2020), which is acontinuation of U.S. application Ser. No. 15/499,439, filed Apr. 27,2017 (issued as U.S. Pat. No. 9,915,513 on Mar. 13, 2018), which claimsthe benefit of U.S. Provisional Application No. 62/454,841, filed Feb.5, 2017, each of which is incorporated herein by reference in itsentirety.

FIELD

The present disclosure relates generally to electronic ignition circuits(“EIC”) for controlling and inducing the ignition of explosivesubstances. More specifically, an EIC controls an igniter/detonator in awell perforation system containing an explosive or pyrotechnic substanceused in oil and natural gas wells, are described herein.

BACKGROUND

Many different commercial activities employ one or more explosive,pyrotechnic and gas-producing substances (herein, “explosivesubstances”) to achieve a variety of engineering and ultimatelycommercial objectives. For example, explosive substances are used in theoil and natural gas industries to enhance production in wells. Once apromising location has been identified, and the necessary rightssecured, the creation of such wells typically begin with drilling aborehole into the ground to reach sought-after deposits of oil and/ornatural gas. To prevent collapse of the borehole, a casing is oftenco-axially inserted into the borehole. In most situations, cement ispumped into a more or less annular space between the cylindrical casingand the larger cylindrical borehole wall to mechanically stabilize thewell. While this method improves mechanical stabilization of the well,unfortunately, it also isolates inner portions of the casing, (i.e., thewellbore), from the sought-after deposits of oil and/or natural gas.

A perforating gun system employing explosive components is typicallylowered into the casing in the borehole via a wireline or tubingconveyed. The wireline is often unrolled from a motorized spool attachedto pulleys and a wireline-truck on the surface (surface truck) adaptedto this purpose. In other circumstances, derricks, slips and othersimilar systems take the place of the surface truck. These provide anoperator with an ability to raise and lower the perforating gun systeminside the well. The wireline cable provides both a physical connectionand an electrical connection between the equipment on the surface andthe perforating gun system. The purpose of the perforating gun system isto create perforations in the casing, cement, borehole wall and, to somedegree, adjacent geologic formations, to enable oil and/or natural gasto flow into the casing. Selective perforating gun systems often includemore than one perforating gun, physically and electrically connectedwith each other in one tool string, which is then connected to thewireline. Generally, the tool string is conveyed a considerable distancefrom the surface depending on the depth of the well and the position ofthe intervals that are intended to be perforated.

Each perforating gun typically includes multiple explosive charges, suchas shaped charges, that include an explosive substance, and anelectrically-initiated igniter or detonator to detonate the explosivesubstance. An electrical signal from the wireline causes theelectrically-or electronically initiated igniter or detonator todetonate the explosive substance, forcing a high energy perforating jetout of the perforation gun into a side of the casing at a high velocity,thereby perforating the casing, cement, borehole and adjacent geologicformation. Because the oil and natural gas industries have been drillingboreholes of greater depths and lengths in search of resources, theability to detonate and perforate selectively has taken on increasingimportance. The ability to more precisely apply one or a series ofdetonations, as well as the ability to cause detonations further awayfrom surface equipment, makes it desirable to have better control overperforation systems inside wells.

BRIEF DESCRIPTION

An exemplary embodiment of an electronic ignition circuit may include alogic circuit and an ignition circuit electrically coupled to the logiccircuit. The logic circuit may include a microcontroller and a switchingcircuit configured to switch from a first detonator or igniter to asecond detonator or igniter in response to a signal from themicrocontroller. The ignition circuit may include a capacitordischarging circuit configured to discharge a firing capacitor through afuse head. The capacitor discharging circuit may include an ignitionswitch configured to remain actively closed after the firing capacitoris discharged through the fuse head.

An exemplary embodiment of an electronic ignition circuit may include alogic circuit, an arming switch configured to close in response to anarming code, thereby charging a firing capacitor, and configured to stayclosed until receipt of a firing code, and an ignition circuitelectrically coupled to the logic circuit. The logic circuit may includea microcontroller and a switching circuit configured to switch from afirst detonator or igniter to a second detonator or igniter in responseto a signal from the microcontroller. The ignition circuit may include acapacitor discharging circuit configured to discharge the firingcapacitor through a fuse head.

An exemplary embodiment of an electronic ignition circuit may include alogic circuit, an ignition circuit electrically coupled to the logiccircuit, and a shot detection circuit. The logic circuit may include amicrocontroller and a switching circuit configured to switch from afirst detonator or igniter to a second detonator or igniter in responseto a signal from the microcontroller. The ignition circuit may include acapacitor discharging circuit configured to discharge a firing capacitorthrough a fuse head. The shot detection circuit may be configured tomeasure a voltage across the firing capacitor before discharging throughthe fuse head and to measure the voltage across the firing capacitorafter discharging through the fuse head.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures depict embodiments for purposes of illustration only. Oneskilled in the art will readily recognize from the following descriptionthat alternative embodiments of the structures illustrated herein may beemployed without departing from the principles described herein,wherein:

FIG. 1 is a block diagram of an exemplary embodiment of an EIC forcontrolling at least one detonator, according to the present disclosure;

FIG. 2 is a flowchart of an exemplary embodiment of the EIC of FIG. 1for controlling at least one detonator, according to the presentdisclosure;

FIG. 3 is a block diagram of an exemplary embodiment having a pluralityN of EIC each for controlling at least one detonator, according to thepresent disclosure;

FIG. 4 is a timing diagram of an exemplary embodiment of an EIC forcontrolling at least one detonator, according to the present disclosure;

FIG. 5 is a schematic diagram of an EIC for controlling at least onedetonator, according to the present disclosure;

FIG. 6 is a block diagram of an EIC for controlling at least onedetonator, according to the present disclosure;

FIG. 7A is a timing diagram of an exemplary embodiment of an EIC forcontrolling at least one detonator, according to the present disclosure;

FIG. 7B is an equation diagram of an exemplary embodiment of an EIC forcontrolling at least one detonator, as shown in FIG. 7A, according tothe present disclosure;

FIG. 8A is a cross-sectional side view of an exemplary embodiment of adetonator having an electronic ignition circuit (“EIC”), according tothe present disclosure; and

FIG. 8B is a cross-sectional side view of an exemplary embodiment of adetonator having an EIC, according to the present disclosure.

DETAILED DESCRIPTION

The following description and drawings are illustrative and are not tobe construed as limiting. Numerous specific details are described toprovide a thorough understanding of the disclosure. However, in certaininstances, well-known or conventional details are not described in orderto avoid obscuring the description.

Reference in this specification to “one embodiment,” “an embodiment” orthe like means that a particular feature, structure, characteristic,advantage or benefit described in connection with the embodiment may beincluded in at least one embodiment of the disclosure, but may not beexhibited by other embodiments. The appearances of the phrase “in oneembodiment” in various places in the specification are not necessarilyall referring to the same embodiment, nor are separate or alternativeembodiments mutually exclusive of other embodiments. Similarly, variousrequirements are described which may be requirements for someembodiments but not for other embodiments. Terms such as “first,”“second,” “forward,” “rearward,” etc. are used to identify one elementfrom another, and unless otherwise specified are not meant to refer to aparticular order or number of elements. The singular forms “a,” “an” and“the” include plural referents unless the context clearly dictatesotherwise. The specification and drawings are to be regarded in anillustrative sense rather than a restrictive sense. Variousmodifications may be made thereto without departing from the spirit andscope as set forth in the claims.

Described herein are example embodiments of an electronic ignitioncircuit (“EIC”) for controlling at least one detonator. The examplesdiscussed herein are intended to be illustrative only to assist inexplanation of the apparatuses, devices, systems and methods described.Features or components shown in the drawings or discussed below shouldnot be taken as mandatory for any specific implementation of any ofthese the apparatuses, devices, systems or methods unless specificallydesignated as mandatory. For ease of reading and clarity, certaincomponents, modules, or methods may be described solely in connectionwith a specific figure. Any failure to specifically describe acombination or sub-combination of components should not be understood asan indication that any combination or sub-combination is not envisioned.Also, for any methods described, regardless of whether the method isdescribed in conjunction with a flow chart, it should be understood thatunless otherwise specified or required by context, any explicit orimplicit ordering of steps performed in the execution of a method doesnot imply that those steps must be performed in the order presented butinstead may be performed in a different order or in parallel.

Referring to FIG. 1 , a block diagram of an exemplary embodiment of anEIC 1000 for controlling at least one detonator 8000 (see, for instance,FIGS. 8 a and 8 b ), according to the present disclosure, is shown. Insome embodiments, the EIC 1000 includes a protection circuit 100, aninput circuit 200, a logic circuit 300 and an ignition circuit 400. Theprotection circuit 100 includes an input terminal, an output terminaland a common (com) terminal, as shown in FIG. 5 , electrically connectedto the input line, the output line and the common line, respectively.Returning to FIG. 1 , the protection circuit 100 protects the EIC 1000from excessive transient voltages beyond a predefined maximum, such asvoltage spikes, that could otherwise cause damaging currents in the EIC.In some embodiments, the protection circuit 100 includes at least one ormore of varistors and/or suppressor diodes to protect against excessivetransient voltages by shunting the current created by excessive voltagesaway from other circuits in the EIC 1000.

The input circuit 200 is electrically connected to the protectioncircuit 100. The input circuit receives electrical power from theprotection circuit and exchanges communications signals with surfaceequipment. The input circuit 200 includes a bridge rectifier. Returningto FIG. 1 , the input circuit 200 exchanges signals with the logiccircuit 300.

The logic circuit 300 is electrically connected between the inputcircuit 200 and the ignition circuit 400. The logic circuit 300 receiveselectrical power from the protection circuit and exchangescommunications signals with surface equipment through the input circuit200. In some embodiments, the logic circuit 300 includes an answer backcircuit 310, a supply voltage circuit 320, a microcontroller 330, a codedetection circuit 340 and a switching circuit 350. In general, theanswer back circuit 310 provides a signal output back to the surfaceequipment to indicate a result of a command or test. For example, insome embodiments, the EIC receives four (4) codes each having adifferent combination of signals of eight (8) coded bits (one byte). Insome embodiments, the four codes are designated as Code A, Code B, CodeC and Code D, respectively, and each have a different function in theEIC 1000. In some embodiments, at a valid reception of Code B, themicrocontroller 330 switches a resistor in the answer back circuit 310to increase the current flow for answer back to surface equipment incommunication with the EIC 1000. In some embodiments, the supply voltagecircuit 320 converts voltages from the protection circuit 100 and inputcircuit 200 to voltage levels acceptable to the logic circuit 300. Insome embodiments, the microcontroller 330 exchanges signals, such asCodes A-D, with surface equipment to control detonation as describedherein. In some embodiments, the code detection circuit 340 detects anddistinguishes between each of the Codes A-D. The microcontroller 330 maybe programmed to detect the codes from the code detection circuit 340.In some embodiments, the switching circuit 350 increases current on theinput line to be compatible with previous perforation systems.

The ignition circuit 400 is electrically connected to the logic circuit300. The ignition circuit 400 is controlled by the logic circuit 300 tostore electrical energy and cause ignition of an explosive substance ina perforation gun (not shown). In some embodiments, the ignition circuit400 includes a capacitor charging circuit 410, a voltage limiter 420, acapacitor discharging circuit 430 and a shot detection circuit 440. Insome embodiments, the microcontroller 330 causes the capacitor chargingcircuit 410 to begin charging a firing capacitor used to causeddetonation in response to receipt of Code C, as described herein. Insome embodiments, the voltage limiter 420 includes a Zener diode tolimit voltage applied to the capacitor charging circuit 410 to protectthe capacitor at high temperatures often found underground. In someembodiments, the capacitor discharging circuit 430 controls the ignitionof a detonator. In some embodiments, the detonator includes anelectrically-initiated fuse head. In some embodiments, the shotdetection circuit 440 detects detonation of an explosive substancecaused by the electrically-initiated fuse head. The shot detectioncircuit 440 includes an integrated shot detection feature. A measurementis made of a voltage across the firing capacitor shortly before andshortly after the fuse head is ignited to determine whether a correctdischarge took place. According to an aspect, the shot detection circuit440 is active after discharging the firing capacitor. If the measuredvoltage is in the expected pre-ignition range shortly before the fusehead is ignited and in the expected post-ignition range shortly afterthe fuse head is ignited, the shot detection circuit 440 generates aresult signal indicating that a proper detonation occurred; otherwise,the shot detection circuit generates a result signal indicating that aproper detonation has not occurred. The result signal (used to define aresult variable) from the shot detection circuit 440 is transmitted viathe answer back circuit 310 to the surface equipment. Because the shotdetection circuit 440 measures voltage across the firing capacitor bothshortly before and shortly after the fuse head is ignited, the accuracyof the result signal is improved, thereby enabling better control of theperforation system because ignition is known with greater accuracy andprecision. Better control of the perforation system also enables longerwirelines to be advantageously deployed.

Referring to FIG. 2 , a flowchart of the EIC 1000 of FIG. 1 forcontrolling 2000 at least one detonator, according to the presentdisclosure, is shown. In step 2005 the microcontroller 330 in the EIC1000 begins polling for codes received from the surface equipment. Insome embodiments, the four (4) codes recognized by the EIC 1000 include:Code A for incrementing control to a next perforating gun; Code B forcausing the microcontroller 330 to increase the current flow for answerback to surface equipment in communication with the EIC 1000; Code C forarming the ignition circuit 400 electrically coupled to the currentperforating gun; and Code D for firing a current perforating gun withthe ignition circuit 400. In some embodiments, Codes A-D are describedas particular two-digit hexadecimal bits corresponding to the 8 bits inthe code such that none of the hexadecimal bits are repeated in any ofCodes A-D.

In step 2010 the EIC 1000 determines if Code A was received. If Code Awas received, in step 2015, the EIC 1000 closes a selective switch, thenin step 2020 the EIC performs no operation (NOP) and does nothingfurther until the microcontroller 330 in the EIC is reset.Alternatively, if Code A is not detected, then in step 2025 the EIC 1000determines if Code B was received. If Code B was not received, the EIC1000 continues polling in step 2005; if Code B was received, the EICcloses a response switch in step 2030 and begins receiving mode pollingin step 2035. In step 2040, the EIC 1000 determines whether Code C isreceived, indicating that the EIC is being instructed to arm and chargethe firing capacitor. If Code C is not received in step 2040, the EIC1000 continues polling in step 2035; if Code C is received in step 2040,the EIC closes the arming switch charging capacitor in step 2045 andenters receiving mode polling in step 2050.

In step 2055, the EIC 1000 determines whether Code D is received,indicating that the EIC is being instructed to fire and discharge thefiring capacitor. If Code D is not received in step 2055, the EIC 1000continues polling in step 2050, if Code D is received in step 2055, theEIC proceeds to step 2060. According to an aspect, a firing transistoris used to discharge the firing switch through the fuse head. The firingtransistor may remain active closed after the discharge of the firingcapacitor through the fuse head.

In step 2060, the EIC 1000 applies a voltage across the firing capacitorshortly before the fuse head is ignited, the firing switch is thenclosed to initiate the fuse head causing ignition of the explosivesubstance, and shortly after the fuse head is ignited the EIC 1000 againapplies a voltage across the firing capacitor to determine whether acorrect discharge took place. If the correct discharge took place, thefuse head is destroyed. According to an aspect, at least three measuredvoltages are used to set a result variable representing one of asuccessful shot, and a failed shot. In an embodiment, the shot detectioncircuit 440 in the EIC 1000 measures voltage across the firing capacitorin step 2060 shortly before the fuse head is ignited and in step 2065shortly after the fuse head is ignited to determine whether a correctdischarge took place. In step 2070, if the measured voltage from step2060 is in the expected pre-ignition range shortly before the fuse headis ignited and the measured voltage from step 2065 is in the expectedpost-ignition range shortly after the fuse head is ignited, then in step2075, the response switch is opened and the shot detection circuit 440generates a result signal indicating that a proper ignition occurred andproceeds to step 2020, otherwise, the shot detection circuit generates aresult signal indicating that a proper ignition has not occurred andalso proceeds to step 2020.

Referring to FIG. 3 , a block diagram of an exemplary embodiment havinga plurality N of detonators with EIC each for controlling at least onedetonator 3000, according to the present disclosure, is shown. In FIG. 3, each perforation gun is represented by a dashed line box that includesa separate detonator with EIC 1000. More specifically, Gun 1 includes adetonator with EIC 3015, Gun 2 includes a detonator with EIC 3020, Gun Nincludes a detonator with EIC 3025. Gun 1, Gun 2 and Gun N eachrepresent sequentially connected perforation guns wherein N is a wholenumber integer. In some embodiments, N is a whole number integer greaterthan or equal to two. Each perforation gun is connected in parallel toWireline A 3005. Each perforation gun is connected in series to WirelineB 3010 such that Wireline B is electrically connected to EIC 3015, whichis connected to EIC 3020, which is electrically connected to EIC 3025and so forth.

Referring to FIG. 4 , a timing diagram of an exemplary embodiment of anEIC for controlling at least one detonator 4000, according to thepresent disclosure, is shown. In one embodiment, a timeline 4010including communications between transmitting and receiving surfaceequipment controlled by an operator and an EIC 1000 is shown. During thetimeline 4010, a first Code A 4020 and a second Code A 4030 istransmitted by the surface equipment and received by the EIC 1000,causing a third EIC in a chain of N EICs to be selected. Code B 4040 istransmitted by the surface equipment and received by the EIC 1000,causing the EIC to respond as described with regard to FIG. 2 .Returning to FIG. 4 , in some embodiments, a variable amount of timebetween transmission of Code B and Code C is dependent at least in parton operator request. At some variable point along the timeline 4010,Code C 4050 is transmitted by the surface equipment and received by theEIC 1000, causing the EIC to become armed. After Code C 4050 isreceived, Code D is transmitted by the surface equipment and received bythe EIC 1000, causing the EIC to fire the perforation gun by ignitingthe fuse head to detonate the explosive substance.

Referring to FIG. 5 , a diagram of the EIC for controlling at least onedetonator (not shown), according to the present disclosure, is shown.The EIC 5000 includes protection circuit 100. Note that as describedherein, components with identical reference numbers in differentfigures, such as those shown in FIG. 1 and in FIG. 5 are intended todescribe the same component. Similarly, where different referencenumbers are used in different figures, such as the EIC 1000 and EIC 5000in FIG. 1 and FIG. 5 , respectively, such numbering is intended todescribe alternative embodiments. For example, protection circuit 100 inFIG. 1 is also illustrated here in FIG. 5 as protection circuit 100. Theprotection circuit 100 includes an over voltage protection at an input102 electrically connected to an over voltage varistor at an output 104.While not shown, it is contemplated herein that at least one or more ofa varistor and/or a suppressor diode may be used at an input, and atleast one or more of a varistor and/or a suppressor diode may be used atan output. The EIC 5000 includes input circuit 200. The input circuit200 includes a bridge rectifier.

The EIC 5000 includes logic circuit 300. The logic circuit 300 includesan answer back circuit 310, which includes a switch 314. The logiccircuit 300 includes a supply voltage circuit 320, with a DC/DCconverter 324. The logic circuit 300 also includes a microcontroller 330with an internal or external A/D converter. The logic circuit 300further includes a code detection circuit 340, with a signal couplingcircuit 342, which couples the signal to the microcontroller 330. Thelogic circuit 300 still further includes a switching circuit 350, whichincludes at least a switch 351 to the output.

The EIC 5000 includes ignition circuit 400. The ignition circuit 400includes a release of capacitor charging circuit 410, which includes atleast an arm switch 411. The ignition circuit 400 also includes avoltage limiter for firing capacitor circuit 420, which includes a DC/DCconverter with a current limitation 424. The ignition circuit 400further includes a capacitor discharge circuit 430, which includes afiring capacitor 432, a fuse head (detonator) 434, and an ignitionswitch 436. The ignition circuit 400 still further includes a shotdetection circuit 440, which includes two resistors 442 and 444connected as a voltage divider to measure the capacitor voltage.

Referring to FIG. 6 , a block diagram of an exemplary embodiment of anEIC for controlling at least one detonator 6000, according to thepresent disclosure, is shown. The input circuit 600 is electricallycoupled to the input line and the common line. In some embodiments, theEIC 6000 includes an answer back circuit 605, a supply voltage circuit610, a microcontroller 615 and a code detection circuit 620 for signalcoupling and a switching circuit 625. The answer back circuit 605 mayindicate the result of a shot detection. In some embodiments, the EIC6000 also includes an arming switch 630. The arming switch 630 may beactive closed to charge the firing capacitor after receiving an armingcode, and until it receives and reacts to a firing code. The armingswitch 630 may be active again after a time delay that occurs after thedischarging of the firing capacitor through the fuse head, in order torecharge the firing capacitor after ignition of the fuse head. The EIC600 may additionally include a voltage limiter circuit 635, a firingcapacitor 645, a fuse head (detonator) 650, a firing switch 655, and ashot detection circuit 640. The shot detection circuit 640 may beadapted to measure a voltage across the firing capacitor 645 beforedischarging through the fuse head 650, and to measure the voltage afterdischarging through the fuse head 650. According to an aspect, the shotdetection circuit 640 measures the voltage across the firing capacitor645 before the discharging of the firing capacitor 645, after thedischarging of the firing capacitor 645, and/or after the recharging ofthe firing capacitor 645. According to an aspect, the shot detectioncircuit 640 may be active again after discharging the firing capacitor645.

Referring to FIG. 7A, a timing diagram of an exemplary embodiment of anEIC for controlling at least one detonator 7000, according to thepresent disclosure, is shown. The timing diagram represents a coded bitexemplar of the eight bit code of Codes A-D. The left side representsthe coded bit logic “1”, while the right side represents the coded bitlogic “0” exemplar of the eight bit code of Codes A-D. In the coded bitlogic “1” all high and low signal periods for transmitting digital bitsin a code, such as code selected from Codes A-D, are substantially equalor greater than one millisecond. In the coded bit logic “0”, the highsignal period (duty cycle) is a holding factor multiplied by the highsignal period used in the coded bit logic “1”. In some embodiments, thatholding factor is greater than 1.5. As shown in FIG. 7A, the holdingfactor is approximately 3, meaning the high signal period is held forthree times longer in a coded bit logic “0” as opposed to a coded bitlogic “1”. The purpose of high and low signal periods greater than onemilliseconds and of holding the high signal period longer in a coded bitlogic “0” is to offset the longer time needed to raise the voltage inthe long wireline due to increased capacitance. The purpose of theholding factor is to reduce the low signal periods to improve thevoltage supply.

Referring to FIG. 7B, is an equation diagram of an exemplary embodimentof an EIC for controlling at least one detonator as shown in FIG. 7A,according to the present disclosure, is shown. All high and low signalperiods for transmitting digital bits in a code, such as code selectedfrom Codes A-D, are substantially equal and greater than onemillisecond. In coded bit logic “0”, the high signal period (duty cycle)is the holding factor multiplied by the high signal period used in codedbit logic “1”. In some embodiments, that holding factor is greater than1.5.

Referring to FIG. 8A, a cross-sectional side view of an exemplaryembodiment of a detonator 8000 having an EIC for controlling thedetonator, according to the present disclosure, is shown. The detonator8000 includes an input connection 8010, an output connection 8020, acommon connection 8030, an EIC 8040, a fuse head 8050, a primary charge8060 and a secondary charge 8070.

Referring to FIG. 8B, a cross-sectional side view of an exemplaryembodiment of a detonator 8100 having an EIC for controlling thedetonator, according to the present disclosure, is shown. The detonator8000 includes an input line (red) 8010, an output line (blue) 8020, acommon line (black) 8030, an EIC 8040, a fuse head 8050, a primarycharge 8060 and a secondary charge 8070.

Some embodiments herein describe an EIC for controlling at least onedetonator, including a protection circuit, including at least one of afuse, a circuit breaker and an automatic switch In an embodiment, theEIC further includes an input circuit electrically coupled to theprotection circuit. The EIC may include a logic circuit electricallycoupled to the input circuit, and including an answer back circuit, anda switching circuit adapted to switch to the next detonator or igniter.According to an aspect, the EIC includes an ignition circuitelectrically coupled to the logic circuit. The ignition circuit mayinclude a capacitor charging circuit, a capacitor discharge circuit todischarge a firing capacitor through the fuse head, and a shot detectioncircuit adapted to measure a voltage across the firing capacitor beforedischarging through the fuse head and to measure a voltage afterdischarging through the fuse head.

Some embodiments herein describe an electronic ignition circuit forcontrolling at least one detonator, including a protection circuit,including a spark gap, at least one of a fuse, a circuit breaker and anautomatic switch, at least one or more of a varistor and/or a suppressordiode at an input, and at least one or more of a varistor and/or asuppressor diode at an output, an input circuit electrically coupled tothe protection circuit, including a bridge rectifier, a logic circuitelectrically coupled to the input circuit, including an answer backcircuit, and a switching circuit for switching from a first detonator toa next detonator, and an ignition circuit including a capacitor chargingcircuit, and a capacitor discharge circuit to discharge a firingcapacitor through a fuse head.

Some embodiments herein describe a method for controlling at least onedetonator with an electronic ignition circuit, including polling for afirst input signal, determining if the first input signal contains afirst code, closing a selective switch if the first signal contains thefirst code, determining if the first input signal contains a second codeif the first input signal does not contain the first code, closing aresponse switch if the first input signal contains the second code,polling for a second input signal, determining if the second inputsignal contains a second code, closing arming switch and charging firingcapacitor if the second input signal contains the second code, pollingfor a third input signal, determining if the third input signal containsa third code, closing firing switch if the third input signal contains athird code.

It will be understood that various modifications can be made to theembodiments of the present disclosure herein without departing from thespirit and scope thereof. Therefore, the above description should not beconstrued as limiting the disclosure, but merely as embodiments thereof.Those skilled in the art will envision other modifications within thescope and spirit of the devices and methods as defined by the claimsappended hereto.

As used herein, the terms “may” and “may be” indicate a possibility ofan occurrence within a set of circumstances; a possession of a specifiedproperty, characteristic or function; and/or qualify another verb byexpressing one or more of an ability, capability, or possibilityassociated with the qualified verb. Accordingly, usage of “may” and “maybe” indicates that a modified term is apparently appropriate, capable,or suitable for an indicated capacity, function, or usage, while takinginto account that in some circumstances the modified term may sometimesnot be appropriate, capable, or suitable. For example, in somecircumstances an event or capacity can be expected, while in othercircumstances the event or capacity cannot occur—this distinction iscaptured by the terms “may” and “may be.”

As used in the claims, the word “comprises” and its grammatical variantslogically also subtend and include phrases of varying and differingextent such as for example, but not limited thereto, “consistingessentially of” and “consisting of.”

Advances in science and technology may make equivalents andsubstitutions possible that are not now contemplated by reason of theimprecision of language; these variations should be covered by theappended claims. This written description uses examples to disclose thedevice and method, including the best mode, and also to enable anyperson of ordinary skill in the art to practice the device and method,including making and using any devices or systems and performing anyincorporated methods. The patentable scope thereof is defined by theclaims, and may include other examples that occur to those of ordinaryskill in the art. Such other examples are intended to be within thescope of the claims if they have structural elements that do not differfrom the literal language of the claims, or if they include equivalentstructural elements with insubstantial differences from the literallanguages of the claims.

What is claimed is:
 1. An electronic ignition circuit, comprising: alogic circuit comprising: a microcontroller; and a switching circuitconfigured to switch from a first detonator or igniter to a seconddetonator or igniter in response to a signal from the microcontroller;and an ignition circuit electrically coupled to the logic circuit, theignition circuit comprising a capacitor discharging circuit configuredto discharge a firing capacitor through a fuse head, wherein thecapacitor discharging circuit comprises an ignition switch configured toremain actively closed after the firing capacitor is discharged throughthe fuse head.
 2. The electronic ignition circuit of claim 1, furthercomprising: an arming switch configured to close in response to anarming code, thereby charging the firing capacitor, and configured tostay closed until receipt of a firing code.
 3. The electronic ignitioncircuit of claim 2, wherein the arming switch is active again after atime delay, wherein the time delay occurs after the discharge of thefiring capacitor through the fuse head, to recharge the firing capacitorafter ignition of the fuse head.
 4. The electronic ignition circuit ofclaim 3, further comprising a shot detection circuit configured tomeasure a voltage across the firing capacitor: before the discharging ofthe firing capacitor; after the discharging of the firing capacitor; andafter the recharging of the firing capacitor.
 5. The electronic ignitioncircuit of claim 4, wherein the show detection circuit is configured tomeasure at least three measured voltages and set a result variablerepresenting one of a successful shot, and a failed shot.
 6. Theelectronic ignition circuit of claim 1, further comprising a protectioncircuit comprising: at least one of a varistor and a suppressor diode atan input of the protection circuit; and at least one of a varistor and asuppressor diode at an output of the protection circuit.
 7. Theelectronic ignition circuit of claim 1, wherein the logic circuitcomprises a supply voltage circuit configured to convert power to avoltage level acceptable to the logic circuit.
 8. The electronicignition circuit of claim 1, wherein the ignition circuit comprises avoltage limiter for the firing capacitor.
 9. An electronic ignitioncircuit, comprising: a logic circuit comprising: a microcontroller; anda switching circuit configured to switch from a first detonator origniter to a second detonator or igniter in response to a signal fromthe microcontroller; an arming switch configured to close in response toan arming code, thereby charging a firing capacitor, and configured tostay closed until receipt of a firing code; and an ignition circuitelectrically coupled to the logic circuit, the ignition circuitcomprising a capacitor discharging circuit configured to discharge thefiring capacitor through a fuse head.
 10. The electronic ignitioncircuit of claim 9, wherein the capacitor discharging circuit comprisesan ignition switch configured to remain active closed after the firingcapacitor is discharged through the fuse head.
 11. The electronicignition circuit of claim 9, wherein the arming switch is active againafter a time delay, wherein the time delay occurs after the discharge ofthe firing capacitor through the fuse head, to recharge the firingcapacitor after ignition of the fuse head.
 12. The electronic ignitioncircuit of claim 11, further comprising a shot detection circuitconfigured to measure a voltage across the firing capacitor: before thedischarging of the firing capacitor; after the discharging of the firingcapacitor; and after the recharging of the firing capacitor.
 13. Theelectronic ignition circuit of claim 12, wherein the shot detectioncircuit is configured to set a result variable indicating a successfulshot or a failed shot based on a comparison of the voltage across thefiring capacitor before the discharging of the firing capacitor, thevoltage across the firing capacitor after the discharging of the firingcapacitor, and the voltage across the firing capacitor after therecharging of the firing capacitor.
 14. The electronic ignition circuitof claim 9, wherein the logic circuit comprises a supply voltage circuitconfigured to convert power to a voltage level acceptable to the logiccircuit.
 15. The electronic ignition circuit of claim 9, wherein theignition circuit comprises a voltage limiter for the firing capacitor.16. An electronic ignition circuit, comprising: a logic circuitcomprising: a microcontroller; a switching circuit configured to switchfrom a first detonator or igniter to a second detonator or igniter inresponse to a signal from the microcontroller; an ignition circuitelectrically coupled to the logic circuit, the ignition circuitcomprising a capacitor discharging circuit configured to discharge afiring capacitor through a fuse head; and a shot detection circuitconfigured to measure a voltage across the firing capacitor beforedischarging through the fuse head and to measure the voltage across thefiring capacitor after discharging through the fuse head.
 17. Theelectronic ignition switch of claim 16, further comprising a firingtransistor to discharge the firing capacitor through the fuse head,wherein the firing transistor remains active closed after dischargingthe firing capacitor through the fuse head.
 18. The electronic ignitioncircuit of claim 16, wherein the shot detection circuit is configured tomeasure the voltage across the firing capacitor before the dischargingof the firing capacitor, after the discharging of the firing capacitor,and after the recharging of the firing capacitor.
 19. The electronicignition circuit of claim 18, wherein the shot detection circuit isconfigured to set a result variable indicating a successful shot or afailed shot based on a comparison of the voltage across the firingcapacitor before the discharging of the firing capacitor, the voltageacross the firing capacitor after the discharging of the firingcapacitor, and the voltage across the firing capacitor after therecharging of the firing capacitor.
 20. The electronic ignition circuitof claim 16, further comprising an arming switch in electricalcommunication with the firing capacitor, the arming switch beingconfigured to close in response to an arming code, thereby charging thefiring capacitor, and configured to stay closed until receipt of afiring code.